1. Field of the Invention
This invention relates to a method of operating an electric arc furnace in which various raw materials are melted.
2. Description of the Prior Art
In an electric arc furnace, an electric arc is extended from an arc electrode by supplying it with electric power from an arc furnace transformer and metallic raw materials are melted by the heat due to the electric arc. At present, in companies which operate furnaces of this kind, melting conditions are determined by the following steps and the melting operation is put into practice under the following conditions. First when raw material to be molten is provided, a time internal necessary for melting the raw material is determined on the basis of past experience. The electric power which must be provided to the electric arc furnace in order to melt the raw material in the determined time interval is then determined. An electric arc current level necessary to supply the electric power is further calculated. The melting operation is performed with the calculated current level. Consequently, if factors such as the kind and quantity of the raw material are changed or the time interval for melting is varied, the input electric power and accordingly the electric arc current level are changed.
Under these circumstances, when the specific electric power consumption, defined as the electric energy consumed per unit mass of raw material to be melted, is considered, such power consumption has ultimately been determined in connection with the kind of the raw material and the time interval for melting.
Applicants have provided a method for melting by which the specific electric power consumption is held down to the minimum value and electric power can be saved.